Single coil would work better for you I think. I've heard that alot of people use the dual coils on PV's like yours, in fact I used them myself on my eGo, but I think I've read since then that it's not good for the battery life? Maybe someone else more knowlagable will come and share with you on that score. But if you're looking to hold more juice, you might want to look into tanks. I've gotten into tanks and haven't looked back! lol!